Europe has improved its air quality in recent decades. Emissions of many pollutants were curbed successfully, but particulate matter and ozone pollution in particular continue to pose serious risks to the health of Europeans.

In many cities now, the pollution is so substantial that it’s almost impossible to see the stars at night.

Justine Lepaulard, France (ImaginAIR)

London, 4 December 1952: A dense fog started settling over the city; the breeze stopped. In the following days, the air over the city stood still; coal burning released high levels of sulphur oxides and added a yellowish hue to the fog. Hospitals were soon filled with people suffering from respiratory diseases. At its worst moment, visibility was so poor at various locations that people could not see their own feet. During the Great Smog of London, between 4 000 and 8 000 additional people — mostly infants and elderly people — are estimated to have died on top of the average death rate.

Serious air pollution in Europe’s large industrial cities was quite common in the 20th century. Solid fuels, coal in particular, were often used to fuel factories and heat homes. Combined with winter conditions and meteorological factors, there were many days when very high levels of air pollution would hover over urban areas for days, weeks, and months at a time. In fact, London was known for its air pollution episodes since the 17th century. By the 20th century, London’s smog was considered one of the characteristics of the city, and had even earned its place in literature.

(c) Ted Russell | Getty Images

Taking action led to real improvements in air quality

Much has changed since then. In the years following the Great Smog, increased public and political awareness led to legislation aimed at reducing air pollution from stationary sources such as homes, commerce and industry. In the late 1960s, many countries, not just the United Kingdom, had started to pass laws to tackle air pollution.

In the 60 years since the Great Smog, Europe’s air quality has improved substantially, largely due to effective national, European and international legislation.

In some cases, it became clear that the air pollution problem could be solved only through international cooperation. In the 1960s, studies showed that the acid rain that was causing the acidification of Scandinavian rivers and lakes was caused by pollutants released into the air in continental Europe. The outcome was the first international legally binding instrument to deal with problems of air pollution on a broad regional basis, namely the United Nations Economic Commission for Europe’s Convention on Long-range Transboundary Air Pollution (LRTAP) of 1979.

Technological developments, some of which were prompted by legislation, have also contributed to improving Europe’s air. For example, car engines have become more efficient in using fuels; new diesel cars have particle filters installed; and industrial facilities have started using increasingly more effective pollution-abatement equipment. Measures such as congestion charges or tax incentives for cleaner cars have also been quite successful.

Emissions of some air pollutants, such as sulphur dioxide, carbon monoxide and benzene have been greatly reduced. This has led to clear improvements in air quality and thus also public health. For example, the switch from coal to natural gas was instrumental in reducing sulphur dioxide concentrations: in the period 2001–2010, sulphur dioxide concentrations were halved in the EU.

Lead is another pollutant that has been successfully tackled by legislation. In the 1920s, most vehicles started using leaded petrol to avoid damage to the internal combustion engines. The health impacts of lead released into the air became known only decades later. Lead affects the organs and the nervous system, hampering intellectual development in children in particular. Starting in the 1970s, a series of actions both at European and international level led to the phasing out of leaded additives in petrol used in vehicles. Today, almost all stations monitoring lead in the air report concentration levels well below the limits set in EU legislation.

Where do we stand now?

For other pollutants, the results are less clear. Chemical reactions in our atmosphere and our dependence on certain economic activities make it more difficult to tackle these pollutants.

Another difficulty stems from the way the legislation is implemented and enforced across EU countries. The air legislation in the EU typically sets targets or limits on specific substances, but leaves it to the countries to determine how they will attain those targets.

Some countries have taken many effective measures to tackle air pollution. Other countries have taken fewer measures, or the measures they took proved to be less effective. This can be partly due to different levels of monitoring and different enforcement capacities in the countries.

Another problem in controlling air pollution comes from the difference between laboratory tests and real world conditions. In cases where legislation targets specific sectors such as transport or industry, technologies tested in ideal laboratory settings might appear cleaner and more effective than in real-world uses and situations.

We must also bear in mind that new consumption trends or policy measures not related to air might also have unintended effects on Europe’s air quality.

(c) Cristina Sînziana, ImaginAIR/EEA

"The ancient practice of burning the stubble in the rural areas is still followed in Romania. It is a way of clearing the area for new, rich crops. In addition to its negative impact on nature, I also consider this activity harmful to the local community’s health. As the burning involves a certain number of people to control the fire, the impact is very specific." Cristina Sînziana Buliga, Romania

PM exposure is still high in cities

Current EU and international legislation aimed at tackling PM classifies particles in two sizes — 10 microns in diameter or less and 2.5 microns in diameter or less (PM10 and PM2.5) — and targets direct emissions as well as emissions of precursor gases.

There are substantial achievements on PM emissions in Europe. Between 2001 and 2010, direct emissions of PM10 and PM2.5 decreased by 14 % in the European Union and by 15 % in the 32 EEA countries.

Emissions of PM precursors have also decreased in the EU: sulphur oxides by 54 % (44 % in EEA-32); nitrogen oxides by 26 % (23 % in EEA-32); ammonia by 10 % (8 % in EEA-32).

But these emission reductions have not always resulted in lower exposure to PM. The share of the European urban population exposed to concentration levels of PM10 above the values set by EU legislation remained high (18–41 % for EU-15 and 23–41 % for EEA-32) and showed only a minor decline in the last decade. When taking into account the World Health Organization’s (WHO) stricter guidelines, more than 80 % of the urban population in the EU is exposed to excessive PM10 concentrations.

So if emissions decreased substantially, why do we still have high levels of exposure to PM in Europe? Reducing emissions in a specific area or from specific sources does not automatically result in lower concentrations.

Some pollutants can stay in the atmosphere long enough to be transported from one country to another, from one continent to another, or in some cases around the globe. Intercontinental transport of particles and their precursors can go some way to explaining why Europe’s air has not improved by as much as PM emissions and PM precursor emissions have fallen.

Another reason for the continued high concentrations of PM can be found in our consumption patterns. For example, in recent years, coal and wood burning in small stoves for home heating has constituted a major source of PM10 pollution in some urban areas, in particular in Poland, Slovakia and Bulgaria. This is partly caused by high-energy prices, which induced low-income households in particular to opt for cheaper alternatives.

Just as with PM, the amounts of ozone precursors emitted into the atmosphere have dropped, but there has not been a corresponding decrease in the high concentration levels of ozone. This is partly due to intercontinental transport of ozone and its precursors. Topography and year-to-year variations in meteorological conditions such as in winds and temperatures also play a role.

Despite a decrease in the number and frequency of peak ozone concentrations in the summer months, the exposure of urban populations to ozone still remains high. In the period 2001–2010, between 15 and 61 % of the EU urban population was exposed to ozone levels above EU target values, mostly in southern Europe due to warmer summers. By the World Health Organization’s stricter guidelines, nearly all of the urban residents in the EU were exposed to excessive levels. Overall, ozone episodes are more common in the Mediterranean region than in northern Europe.

But high ozone concentrations are not only an urban phenomenon seen during summer months. Surprisingly, ozone levels tend to be generally higher in rural areas, although fewer people are exposed. Urban areas usually have higher levels of traffic than rural areas. However, one of the pollutants released by road transport destroys ozone molecules through a chemical reaction, and may thus result in lower ozone levels in urban areas. However, the higher traffic levels result in higher PM levels in cities.

(c) Jerome Prohaska, ImaginAIR/EEA

Legislation to reduce emissions

Given that they may originate partly in other countries, the emissions of some of the PM and ozone precursors are covered by the Gothenburg Protocol to the Convention on Long-range Transboundary Air Pollution (LRTAP Convention).

In 2010, 12 EU countries, and the EU itself, exceeded one or more emission ceilings (the allowed amount of emissions) for one or more pollutants covered by the convention (nitrogen oxides, ammonia, sulphur dioxide and non‑methane volatile organic compounds). Ceilings for nitrogen oxides were exceeded by 11 of the 12 countries.

A similar picture emerges from EU legislation. The National Emission Ceilings (NEC) Directive regulates emissions of the same four pollutants as the Gothenburg Protocol but with slightly more stringent ceilings for some countries. Final official data for the NEC Directive indicate that 12 EU countries failed to meet their legally binding emission ceilings for nitrogen oxides in 2010. Several of these countries also failed to meet their ceilings for one or more of the other three pollutants.

Where do air pollutants come from?

The contribution of human activities to the creation of air pollutants is generally easier to measure and monitor than natural sources, but this human contribution varies greatly depending on the pollutant. Fuel combustion is clearly one key contributor and is spread across various economic sectors, from road transport and households to energy use and energy production.

Agriculture is another important contributor to specific pollutants. Around 90 % of the ammonia emissions and 80 % of the methane emissions come from agricultural activities. Other methane sources include waste (landfills), coal mining and long‑distance gas transmission.

More than 40 % of emissions of nitrogen oxides come from road transport, while around 60 % of the sulphur oxides come from energy production and distribution in the EEA member and cooperating countries. Commercial, government and public buildings, and households contribute to around half of the PM2.5 and carbon monoxide emissions.

It is clear that many different economic sectors contribute to air pollution. Bringing in air quality concerns into the decision-making processes for these sectors might not make the newspaper headlines, but it would certainly help improve Europe’s air quality.

Air quality under public scrutiny

What has actually made the international headlines and attracted public attention in recent years was the air quality in large urban areas, especially for the cities hosting the Olympic Games.

Take Beijing. The city is known for its fast‑rising skyscrapers as well as its air pollution. Beijing started systematic air pollution control in 1998 — three years before being officially selected to host the Olympic Games. The authorities took concrete measures to improve air quality ahead of the Games. Old taxis and buses were replaced and dirty industries were relocated or closed. In the weeks prior to the Games, construction work was put on hold and car use was restricted.

Professor C.S. Kiang, one of the leading Chinese climate scientists, talks about air quality during the Beijing games: ‘During the first two days of the Games, the concentration of PM2.5, the fine particles that penetrate deep into the lungs, were around 150 μg/m3. On the second day, it started to rain, the winds turned up and PM2.5 levels dropped sharply and then hovered around 50 μg/m3, which is double the WHO guideline value of 25 μg/m3.’

(c) Rob Ewen | iStock

A similar discussion took place in the United Kingdom ahead of the London Olympics in 2012. Would the air quality be good enough for Olympic athletes, especially the marathon runners or the cyclists? According to the University of Manchester, the London Olympics were not pollution-free, but may still have been the least polluted games in recent years. Favourable weather and good planning seem to have helped; a rather big achievement compared to London in 1952.

Unfortunately the air pollution problem does not disappear after the Olympic spotlights are turned off. In the first days of 2013, Beijing was once again immersed in severe air pollution. On 12 January, official measurements indicated PM2.5 concentrations of over 400 μg/m3, whereas unofficial readings at various locations reached 800 μg/m3.